Submitted to: Journal of Animal Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/3/2006
Publication Date: 6/18/2007
Citation: Scholljegerdes, E.J., Lake, S.L., Westin, T.R., Rule, D.C., Moss, G.E., Nett, T.M., Hess, B.W. 2007. Fatty acid composition of plasma, medial basal hypothalamus, and uterine tissue in primiparous beef cows fed high-linoleate safflower seeds. Jr. of Anim. Sci. 85:1555-1564. Interpretive Summary: It is well established that supplemental fat can have an impact on reproductive function in beef cows. Therefore, it was our objective to examine the effects of supplemental high-linoleate safflower seeds fed to primiparous beef cows during early lactation on fatty acid composition of key tissues involved in reproduction as well as the production of prostaglandin metabolite of which linoleic acid is a precursor. High-linoleate safflower seeds increased plasma concentrations of linoleic acid, conjugated linoleic acid, and total unsaturated fatty acids. In addition, postpartum supplementation of linoleic acid increased fatty acid concentrations of tissues important to reproduction such as the oviduct. Furthermore, prostaglandin production was increased early in the postpartum period. These data would indicate that dietary linoleic acid fed to beef cows in the early postpartum period can alter the concentration of key fatty acids in reproductive tissues, which may potentially influence fertility.
Technical Abstract: The experimental objectives were to evaluate the influence of supplemental high-linoleate safflower seeds on fatty acid concentrations in plasma, medial basal hypothalamus, uterine tissues, and serum 13,14-dihydro-15-keto PGF2' metabolite (PGFM) in primiparous beef cows during early lactation. Beginning 1 d postpartum, 18 primiparous, crossbred beef cows (411 ± 24.3 kg of BW) were fed foxtail millet hay at 1.68% of BW (DM basis) and either a low-fat supplement (control: 63.7% cracked corn; 33.4% safflower seed meal; and 2.9% liquid molasses; DM basis) at 0.35% of BW(n = 9) or a supplement (linoleate) containing 95.3% cracked high-linoleate (79% 18:2n-6) safflower seeds and 4.7% liquid molasses (DM basis) at 0.23% of BW (n = 9). Diets were formulated to be isonitrogenous and isocaloric. The linoleate diet contained 5.4% of DMI as fat vs. 1.2% for control. Beginning 1 d postpartum, cattle were bled every 3 d for collection of serum and plasma. Cattle were slaughtered at 37 ± 3 d postpartum for collection of the medial basal hypothalamus, myometrium, endometrium, caruncular tissue, intercaruncular tissue, and oviduct. Feeding linoleate increased (P = 0.001) plasma concentrations of 18:2n-6, 18:2cis- 9 trans-11 and total unsaturated fatty acids; however, 18:1trans-11 did not differ (P = 0.19) between treatments. Concentrations of 20:5n-3 in the medial basal hypothalamus tended (P = 0.10) to be greater for cattle fed linoleate. Concentrations of fatty acids in the oviduct were greater (P < 0.05) than in other uterine tissues. Cows fed linoleate had greater (P = 0.05) concentrations of 18:3n-3 in the endometrium and less (P = 0.06) 18:2cis-9 trans-11 in the myometrium than cows fed the control. Supplemental fat increased (dietary treatment x day postpartum, P = 0.01) concentrations of PGFM in serum more in linoleate than control cows from d 3 to 9 postpartum. Lipid supplementation early in the postpartum period altered the fatty acid composition of medial basal hypothalamus, uterine tissue, and serum concentrations of PGFM. The most novel observation was that the oviduct appeared to be the most sensitive tissue to additional dietary linoleic acid, which could potentially influence fertility.